Art of refrigeration



1952 E. L. SCHULZ ETA].

ART OF REFRIGERATION- 3 Sheets-Sheet 1 Filed Feb. 2, 1946 FIG. 7

IN VEN TOR. 4 $4M -s Oct. 21, 1952 Filed Feb. 2, 1946 FIG.3

E. L. SCHULZ ET AL ART OF REFRIGERATION FIGJO 3 Sheets-Sheet 2 Oct. 21,1952 E. SCHULZ ETAL. 2,614,393

ART OF REFRIGERATION Filed Feb. 2, 1946 s Sheets-Sheet s FIG.5

trating modifications of the system, shown in Figure 3; and

Figures 11 and 12 are fragmentary views'illustrating modifications ofthe system shown in.

Figure 5.

Referring to the drawings there isshown a compressor 2 of thereciprocating type, although it may be of any desired type, adapted todischarge compressed refrigerant gas through line 3 to a condenser 4.Condenser 4 may be air or water cooled as desired; condenser 4 isillustrated as air cooled by means of fan 5. Condensed refrigerantenters receiver 6 and then proceeds through discharge line I to controlvalve 8, expansion valve 9 and evaporator Iii, returning to compressor 2through suction line i l. Expansion valve 9 operates in the usual mannerunder control of bulb l2 attached to the discharge side of evaporatorill to maintain a predetermined super-heat in the refrigerant dischargedfrom evaporator Iii. As is customary, an equalizerline connectsexpansion valve 9 with suction line H to provide a pressure under thediaphragmof the expansion valve equal to the pressure atthe dischargeend of the evaporator.

When the system operates normally and the condenser pressure asreflected in line 1 remains below a predetermined upper limit of 200pounds, for example, valve 8 remains fully open and the system operatesas if valve 8 were omitted therefrom.

Assuming that the system becomes overloaded due, for example, to thebreak-down of fan 5, used for cooling the condenser (or due to thebreak-down of the water supply if the condenser depends upon water forrefrigerant cooling purposes), then the pressure in condenser 4,receiver 6 and line i rises. If the failure to provide con-' densercooling becomes'so serious as to cause the pressure to rise above thepredetermined maxi mum limit of ZOOpounds in the example given, thendamage to the system would result'unl ess operation was stopped or thecapacity of the system effectively reduced so that only that amount ofrefrigerant was handled which could be condensed effectively.

When the pressure in discharge line i (the condensing pressure) exceedsthe predetermined maximum of 200 pounds, control'valve 8 will operateresponsive to a rise in pressure abovethe set figure to decreaseprogressively'the amount of refrigerant permitted to enter evaporatorl-ll through expansion valve 9; The-volume of re frigerant admitted toevaporator Iii will'decrease as the condensing pressure increases abovethe predetermined maximumof 200 pounds. If the fault in the systemcausing the increase in condensing pressure is due to impairedcondensing action, but assuming some condensing action does take place,then valve 8 will permit a reduced quantity of refrigerant to beadmitted to evaporator it, such reduced volume being the maximum whichthe system can handle without a fur? ther increase in condensingpressure.

Assuming that a pressure of 200 pounds, for example, which is below thedanger point would not be exceeded if only a portion of the normalvolume of refrigerant is permitted to be circulated in the system, thencontrol valve 8 will constri'ct the flow leading to expansion valve 9and evapo- 4 rator lil so that only such percentage of the normal amountof refrigerant will be delivered by the system.

Since such operation at reduced efficiency is undesirable, suitablemeans may be provided for informing the operator of the abnormalconditions. A relay may be provided operative responsive to a rise intemperature in discharge line 1 above an upper limit which will cause asuitable alarm to function; the alarm may take the form of a bell,flashing light or other signal device.

Obviously, under conditions of serious impairment, such as when fan 5breaks down or when force is exerted against diaphragm I5, flexing it-For purposes of illustration, control valve 8'- may take-the form shownin'Figure 2." Considering'Figure 2,controlvalve8 includes a housing l4containing a diaphragm l5 disposed in position therein; A-spring i5 isdisposed adjacent one side of the diaphragm and is adapted to apply apredetermined force thereto. A' stem 1''! carrying valve member I 8 isadapted'to close a port [9 within'housing l6. Under normal conditionsspring [6 flexes diaphragm I5 downward moving stem I! downward thusmoving valve member l8 away from port [9, permitting free flow ofrefrigerant through entrance port 20 intothe housing, through port I9and through discharge'port As pressure increases in discharge line I,

in the opposite direction and raising stem l1 carrying valve member !8to closeport l9 to the required extent. As the condenser pressure againdecreases, spring 16 'flexes diaphragm 15 to move valve member l8 awayfrom port I9 to open port 19 to the free passage of refrigerant.

If desired, in the system illustrated in Figure 1, control means'rnaybeprovided as shown in'Figure 7 for regulating theflow of refrigerantresponsive to variations in load in an area served by the system. Suchmeans may comprise a suitable diaphragm Z2 incorporated in a controlvalve 8, which is actuated by a bulb 23 disposed preferably in the areabeingserved. In such case a decrease in th temperature of "the areabeing served will tend to move control valve 8' toward aclosed positionthus reducing the flow of refrigerant to evaporator l6. The decrease intempera-, tune in the area being. conditioned is reflected by bulb 23which servesto applypressure to diaphragm 22 to urge control valve 8toward a'closed position.

' In a structure of'th'e type contemplated, control valve 8 normallyfunctions to restrict the flow of refrigerant in order to take care ofconditions of overload. It may be actuated, however, as described above'to compensate for conditions of underload; in such case, control valve8" may be employed and actuated to compensate for a reduction in load asreflected by a reduction in temperature within the area beingconditioned.

if desired, a second control valve 24 as shown inFigure 8 maybe disposedin line .1 which .may beactuated by a bulb 25 disposed in the areabeingserved. Such-valve operates similarly to reflected by bulb 25,urges control valvel ktoward-1 a closed position to compensate for thereduction in load, thus decreasing; the; amount. ofi refrigerantforwarded to. evaporatory-tfl.

In'Figure 3, we have illustrated, a, modifiedyform of; our; inventionin, which the functions,performed ,byi expansion valve 9, and.controlyalve E 35 system f t e pe ShOMlILiI-l F gure. lwax'e combined.ir1---a single valve,.,2;.6. Refem'zinaio Figured, control valve 26 isresponsive to-.a.bulb attached to the dischargeside-of evaporator ntmaintain a p et rmined.sup rwheatrin the refrigerant discharged.fromgevaporator; I 0. Valve 26,15 designed to mover toward aaolosedposition. inr ponse to anf-inerease in condense press re bove a pr etrmine maximu thereby decreasing the amount of refrigerant passing toevaporator The structure of a suitable, valve for use in the systemillustrated in Figure 3 is show diagrammatically in Figure 4. As shownin Figure 4, a.

housing 28 contains a diaphragm 29 disposed Within a chamber 30 therein.Diaphragm 29 separates chamber 30 into two compartments 3| and 32.Pressure in compartment 3| is controlled by bulb 21 while pressure incompartment 32 is controlled by suction pressure through equalizer line33. .A stem 34 is secured to diaphragm 29 and carries a valve member 35adapted to close port 36 within the valve. Expansion valves of this typeare well known in the art.

In the structure shown in Figure 4, a bellows 31 is added which carriesa lever 38 connected toa continuation 34' of stem 34. Lever 38 is hingedat point 39. An increase in pressure in discharge line '1 extendsbellows 31 forcing lever 38 to pivot about point 39 and moving valvemember 35 upwardly to close port 36.

If desired, a valve 26 generally similar to valve 26 but designed toalso be responsive to a decrease in temperature in an area beingconditioned to decrease the amount of refrigerant passing to evaporatorID as shown in Figure 9 may be employed. Likewise, as pointed out inconnection with Figure 1, an additional control valve 24 as shown inFigure 10 responsive to room temperature as reflected by bulb 25 may bedisposed in line to govern the amount of refrigerant flowing through theevaporator in accordance with a decrease in temperature in an area oeingserved.

Figure 5 illustrates a further modification of Jur invention in which abypass line 40 is pro- 'Iided connecting discharge line 1 with suctionine The point of juncture of bypass 40 with abova- A; decrease in enigmail'ar, tether-valve shownin. F gure: zrexceptrthat" n' nereaseinrcondenser pressure excrtsqfoma against: diaphragm L5 to openztheyalyeandzthatr a decrease in condenser I pressure-permits.valve;

. member 8=to bemoyccl toward-a positionclosing:

Itrwil l baunderstood the system shown inlil'gz ure 5 may also be:responsive to the temperature of' the area beingserved' by: means ofan-addiftionald-iaphragm-w added'tovalve 4|" as: shown iii-Figure l1which is-actuated, by-a bulb disse posed in the-areabeing served Ifdesired, a suitable valve -45-may be di'sposed inlineflt as: shownin-Fig=ure --12', valve '45 being actuated by a -bulb-4i6 disposedin-thearea being served; todecrease the amount of' refrigerant passing'to theevaporaton The present inventionprovidesca ready-andisimplecontrol arrangement for regulating the production of refrigerationeffect in. response to variations in lea-d conditions. Thesystem soprovidedcoinpensates for overload' conditions arising-fromunforeseencauses. It provides a simple and efiective control for regulating theoperation of an expansion valve to compensate automatically forconditions resulting in undesirable condenser pressures. The controlarrangement so provided is responsive to the pressure of the system, andif desired, may also be responsive to the temperature of the area beingconditioned, thus assuring satisfactory results in operation. Thecontrol arrangement operates effectively to throttle the flow ofrefrigerant to an evaporator When condenser temperature rises above apredetermined maximum. The control arrangement provided effectivelyregulates operation of the system in response to conditions of overloador partial load.

While we have described and illustrated a preferred embodiment of ourinvention, it will be understood our invention is not limited theretosince it may be otherwise embodied within the scope of the followingclaims.

We claim:

1. In a refrigeration system, the combination of a compressor, acondenser, an expansion valve and an evaporator disposed in a closedcircuit, means disposed adjacent the suction line for controlling theoperation of said expansion valve, a bypass extending from the dischargeline to the suction line, the juncture of said bypass with the suctionline being disposed between the discharge end of the evaporator and lineH is located between the discharge end of refrigerant passing into thesuction line cools bulb |2 thus urging expansion valve 9 toward a closedposition and decreasing the amount of refrigerant passing to evaporatorID.

A suitable control valve 4| for this purpose is shown in Figure 6. Suchvalve is generally simthe control means for the expansion valve, asecond valve in said bypass, said bypass having an orifice thereinadapted to regulate the quantity of refrigerant passing therethrough,said second valve being responsive to an increase in condenser pressureabove a predetermined level to move toward an open position permittingrefrigerant to pass through said bypass, passage of refrigerant throughthe bypass into the suction line actuating said control means to operatethe expansion valve.

2. A refrigeration system according to claim 1 in which a control valveis provided in the discharge line to meter the quantity of refrigerantpassing to the expansion valve, and means are provided to actuate saidcontrol valve in response to a decrease in room temperature below apredetermined level to decrease the quantity of refrigerant passing tothe expansion valve.

3. In a refrigeration system, the combination of a compressor, acondenser connected to the compressor, an evaporator, a dischargelli-neconnecting the condenser and the evaporator;

anexpansion valve in said line, a suction line connecting the evaporatorand the compressor, a thermal bulb disposed adjacent the suction lineadapted to control operation of said expansion valve, a bypassconnecting the discharge line and'the suction line, the juncture of thebypass with the suction line being placed-between the discharge end ofthe evaporator and the thermal bulb, a valve in said bypass, an orificein said bypass, said valve under normal conditions of operationremaining in a substantially closed position and being adapted inresponse to an increase in condenser pressure above a predeterminedlevel to tend to open to permit liquid refrigerant to enter the bypass,

passage of liquid refrigerant through the bypass to the suction lineactuating said thermal bulb thereby tending to move the expansion valvetoward a closed position to decrease the quantity of refrigerant passingto the evaporator.

EDWARD L. SCHU'LZ. EDWARD A. BAILEY.

8, REFERENCES CITED.

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,591,302 Franklin July 6, 19261,782,687 Hoffman Nov. 25, 1930 2,080,358 Kucher May 11, 1937 2 ,091,787Locke Aug. 31, 1937 2,183,343 Alsing 'Dec. 12, 1939 2,196,777 Otto Apr.9, 1940 2,196,778 Dodge Apr. 9, 1940 2,258,458 Lange Oct. 7, 19412,344,215 Soling et a1 Mar. 14, 1944 2,415,338 Carter Feb. 4, 19472,434,593 Schulz et a1 Jan. 13, 1948 2,453,439 Hubbard Nov. 9, 194,8,

